Short-circuiting device.



E. 131151011 SHORT OIRCUITING DEVICE.

APPLICATION FILED FEB414, 1914.

Patented Sept. 22, 1914.

///IIIIIIII/I\IIIIIII7 I UNITED STATES PATENT OFFICE.

EDWARD BRETCH, OF ST. LOUIS, MISSOURI.

snon'r-omcorrma DEVICE;

Patented Sept. 22, 1914.

Application filed Tebruary-M, 1914. Serial No. 818,674.

1,111,358. Specification of Letters Patent.

To all whom it may concern:

Be it known that I, EDWARD BnE'roH, a citizen of the United. States, residing at the city of; St. Louis, State of Missouri, haveinvented a certain new and useful-Improvement in Short-circuiting Devices, of which the following is a full, clear, and exact description, such as will enable others skilled in the art to which it a'ppertainsto make and use the same, reference being had to the-accompanying drawings, forming part of this specification, in which Figure 1. is a vertical section through a motor equipped with my improved short circuiting device. Fig. 2 is a side view of. a

'motorpartly in section showing the comm lr,

tator and short circuiting device in elevation. Fig. 3 is a detail illustrating the relationship of parts when a short circuiting plate is in position to short-circuitthe-armature.

My invention relates to improvements in ashort circuiting device for alternating current motors having a series starting characteristic and designed to .be short-circuited when the ,motor has reached its running speed.

The object of my invention is to improve generally upon the constructionof such devies with the idea of simplifying their construction and securing a more positive action, and a better rubbing contact.

W ith these and other objects in view, which will be obvious, it will be understood by reference to the drawings that 1 represents the motor casing, Z the armature shaft, and i the armature. Mounted on the shaft 2 isa collar 5 which is designed to support the commutator segments 6, the same being clamped thereon by the clamping ring 7 which is adjustable by means of the bolts 8.

Slidable longitudinally on the shaft is a short circuiting ring with an annular ridge 10 forming a mounting and a fulcrum for the short circuiting plates 11. These short circuiting plates 11 are of a general 'L-shape having a transversely extending arm provided with a hooked end adapted to engage the ridge 10, and a comparatively heavy arm extending radially of the shaft and formed with a contact making portion 11. A spring12 bear+ ing at one end against the short circuiting ring {9 and at the other against a nut or stop member 14, tends to press ring 9 inwardly and-hold the short circuiting plates 11 re- 9 which is provided tracted against stop ringv 14 When short circuitlng plates Here in this position, they are out of contact with the commutator-f segi-- ments 6 and the various segments with their related armaturewindings are independent Thisisthe starting; position. of the short circuiting plates 1,1,andtwith the platesin' th s positicn the nioton-is adapted to start as repulsion motorJ Them-the armature shaft shall haveattained sufiicient speed so that-the force of the centrifugal tendency of thegplates 11 will overcome the power of spring 12, the outer ends of theplates 11 will move out radiallyjfromz the, shaft, draw.- lng the ring 9 outwardly against the'tension' of, spring 12.- In this position, the contact making portions 11 of the .short rcircuiting plates, -will engage the ends, of .the commutater segments 6 and short-circuit the segments and the armature windings through theplates 11 and the ring .9, The generaloperaltion of shortacircuitinga motor in this fashion is well known in the art, but theme-re ticular form and arrangement of my short circuiting plates renders the device illustrated particularlyeflicient and an improve ment upon the devicesheretoforeemployed. Because of the L-shape of the plates 11 and the disposal of ring 9 and the, commutator segments 6, ,very, heavy -.contactpressure between theplates 11 and segments 6 is secured. This ;.i's due to the fact that, the spring 12. acting in, a direction longitudi nally of the shaft, and the centrifugal force a ti g t p a s in dir ction. r dially cf the shaft and at substantially righta'irgles to the force of the spring, the resulting pull on the outer extremities of the plates 11 is directly against the ends of thecommutator 95 is secured by having the fulcrum point and 'the contact in such relationship to each other that a'line 100 :from one to the other intersects the commu-,

point of the segments disposed tator segments when the plates are in operating position. i

A further advantageof the device as constructed lies in the fact that age of considerable length between the power end of the plates, represented by their heavy radial arms, and their fulcrum end. This renders the lates more responsive to the centrifugal in of their weight where it is most efficient. This construction also provides the rubbing there is a leveruence, and disposes most contact on a vertical face of the commutator, and thereby provides an added assurance against sparking and had contact as the vertical face does not afford a resting place for dirt.

What'I claim is:

1. In an electric motor, a centrifugal short circuiting device comprising the combination of an armature shaft, commutator segments carried thereon, and having contact faces disposed normal to the shaft, and short circuiting plates carried on said shaft and adapted to cooperate with said commutator segments; said short circuiting plates being of general L-shape and each having one arm directed longitudinally of said shaft and the other arm radially of said shaft, said first mentioned arm being fulcrumed on a member movable longitudinally of the shaft and said radial arm being adapted to cooperate with a contact face of a commutator segment. i

2. In a motor, a centrifugal short circuiting device comprising the combination of commutator segments carried by the shaft, and having contact faces disposed normal thereto, a short circuiting member movable i longitudinally on the shaft between the g same and the commutator segments, a plu- 5 rality of short circuiting plates each fulcrumed at one end on said short circuiting member and having its free end adapted to cooperate with a face of a commutator segment lying normal to the shaft, and a yielding pressure means cooperating with saidshort circuiting member and tending to move the same in a direction away from the free ends of said short circuiting plates.

3. In an electric motor, a short circuiting device comprising the combination of a l revoluble shaft, short circuiting plates car- I ried by said shaft and each fulcrumed at one end to a short circuiting member movable longitudinally on said shaft, the other end of each of said short circuiting plates being adapted to swing radially from said shaft under centrifugal influence, commutator i segments carried by said shaft and having faces extending transversely of said shaft intermediate-the extremities of said short circuiting plates, and yielding pressure means tending to. move saidv short circuiting plates on saidshaft in a direction opposite their free ends; said free ends of the short circuiting platesbeing adapted to cooperate with the transversely disposed faces of said commutator segments.

4L. In an electric motor, a short circuiting device comprising the combination of a revoluble shaft, commutator segments carried thereon, short circuiting plates carried on said shaft and each fulcrumed at one end radially nearer the shaft than the commutator segments, the other end of each of said short circuiting plates being adapted to move away from said shaft, said commutator segments having faces disposed transversely of said shaft and positioned intermediate the longitudinal extremities of said short circuiting plates and adapted to coop-.

erate with the free ends of said short circuiting plates, and yielding pressure means operable upon the fulcrumed ends of said short circuiting plates to hold the free ends thereof in contact with the commutator segments when said ends are swung away from said shaft.

In testimony whereof I hereunto aflix my signature in the presence of two witnesses, this 12th day of February, 1914.

EDWARD BRETCH.

Witnesses:

M, P. SMITH, G. S. BUTLER. 

